Thermosensitive channels in skin keratinocytes and/or in sensory neurons innervating the skin open in response to heating or cooling and mediate our perception of ambient temperature. We have found that some basal epidermal cells, as well as matrix keratinocytes of the hair follicles, express the TRPML3 channel. We have also observed that this channel opens in response to changes in temperature that go from cold towards the homeostatic temperature of skin. Here we propose to address the following questions. (1) Which epithelial cells express TRPML3 channels, and at which stages of epidermal and folliclular epithelial development do these express these cation channels? (2) Do these cells display cold-to-warm thermosensitive currents and are these currents mediated by their endogenous TRPML3 channels? (3) Does TRPML3 elimination affect hair follicle or epidermal morphology? These studies aim at elucidating the function ofTRPML3 channels in the epidermis and hair follicle, and may lead to further studies of how the skin, including the vasculature and eccrine glands, detect and respond to changes in temperature.